Fluid flowmeter

ABSTRACT

Liquid flow rate in a conduit is measured by measuring the time it takes a gas bubble to interrupt two spaced light beams passing through a flowmeter cell. The bubble is introduced upstream of the cell by a fluidic device and passes between a light and a photoelectric cell, which signals an electronic counter. As the bubble passes between a second light and photoelectric cell combination, another signal goes to the counter, which is calibrated to read in whatever units may be desired, such as gallons per minute.

United States Patent Arutunian et al.

[54] FLUID FLOWMETER [72] Inventors: Gregory Arutunian, Detroit; DavidK. Wilburn, Troy, both of Mich.

[73] Assignee: The United States of America as represented by theSecretary of the y.

[22] Filed: Nov. 2, 1970 [21] Appl. No.: 86,008

[52] US. Cl. ..73/ 194 E [51] Int. Cl ..G01f 3/00 [58] Field of Search..73/l94 E, 194 R [56] References Cited UNITED STATES PATENTS 3,403,55510/1968 Versaci et a1 ..73/l94 3,336,803 8/1967 Thorndike ..73/l94 [451Sept. 5, 1972 FOREIGN PATENTS OR APPLICATIONS 1,934,583 1/1970 Germany..73/l94 Primary Examiner-Richard C. Queisser Assistant Examiner-HerbertGoldstein Attorney-Harry M. Saragovitz, Edward J. Kelly, Herbert Berland John F. Schmidt [57] ABSTRACT Liquid flow rate in a conduit ismeasured by measuring the time it takes a gas bubble to interrupt twospaced light beams passing through a flowmeter cell. The bubble isintroduced upstream of the cell by a fluidic device and passes between alight and a photoelectric cell, which signals an electronic counter. Asthe bubble passes between a second light and photoelectric cellcombination, another signal goes to the counter, which is calibrated toread in whatever units may be desired, such as gallons per minute.

5 Claims, 1 Drawing Figure P'A'TENTEDSEP 5 I972 3.688.574

/NVE/V7'0R5 GREGORY ARUTU/V/AN DA W0 K. W/L BUR/V H. M. Soragow'tz E. J.Kelly h. Ber/ 8 John F. Schmidt ATTO/PNE Y5 FLUID FLOWMETER Theinvention described herein may be manufactured, used, and licensed by orfor the Government for governmental purposes without payment to us ofany royalty thereon.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to the measurement of the rate of fluid flow, and especiallyliquid flow in a closed conduit and having no free surface.

2. The Prior Art Conventional methods of measuring liquid flow ratesinvolve the rotation of a turbine in a magnetic field to produce anelectrical frequency output which is proportional to the flow rate;using an orifice or a venturi, the flow rate being proportional topressure drop; linear displacement of a ball or a plug in a constantdiameter passage; measuring the voltage induced across a conductingliquid flowing through a magnetic field; and measuring the coolingeffect of a flowing liquid. Such methods all have disadvantages ordifficulties of one kind or another, including high cost, requiring apermanent installation, requiring constant filtration, and the like.

SUMMARY OF THE INVENTION The conduit carrying the liquid for which theflow rate is to be measured is connected with a flowmeter cellconsisting of an elongated section of liquid conduit. Twoenergy-sensitive means are spaced along the cell to receive radiantenergy transmitted through the cell from suitable sources. Upstream ofthe cell, a Y connection in the conduit is used to introduce a gasbubble into the conduit, by means of an OR-NOR gate, specifically avariable one-shot fluidic multivibrator of which the OR leg is connectedwith the Y, preferably through a capillary tube, the supply leg isconnected with a suitable source of gas under pressure, and the controlpressure tap is connected with any suitable source of pulsed fluidpressure such as a NOR fluidic oscillator. An electronic counter isconnected to receive the output signals from the spaced light-sensitivemeans and can be calibrated to read out in any desired units.

It is accordingly an object of this invention to provide a device togive a running reading of the rate of liquid flow in a conduit, whichmeter can be inexpensively made and is more reliable and more adaptablethan conventional meters which accomplish the same or similarobjectives.

THE DRAWING The sole FIGURE of the drawing is a schematic illustrationof the preferred combination of elements making up a fluid flowmeter inaccordance with this invention.

DETAILED DESCRIPTION A pump 2 is connected to a source (not shown) ofliquid by a conduit 4 and discharges into a conduit 6, and it is therate of fluid flow in conduit 6 that is to be measured. Conduit 6includes one input leg and the output leg of a Y shown generally at 8,the other input leg 10 of the Y being connected with a bubble sourcethrough a capillary tube 12.

In a preferred embodiment of the invention a stream of bubbles issupplied by means which includes a variable one-shot fluidicmultivibrator 14 in which the OR leg 16 is connected to the capillarytube 12 as indicated above. A flowmeter according to this invention hasbeen successfully operated with fluidic element catalog number 190985Variable One Shot, of the Fluidic Products Dept, Corning Glass Works,Corning, New York 14830. A suitable source of pressure 18 is connectedwith the supply port of the fluidic device by means of a conduit 20.

A source of control pressure 22 is connected with the control tap of thefluidic device by a conduit 24. Control pressure source 22 can be assimple as a manually operable rubber bulb; such a source gives theoperator control over the device and permits the operator to inject oneor more bubbles at will. If a continuous stream of bubbles is desired toprovide a continuous flow rate reading, a fluidic oscillator may be usedas the source of control pressure 22. Other sources of pressure pulseswill occur to those skilled in the art and may be used.

Inhibit port 26 and auxiliary port 28 are, in this invention, connectedwith a capacitor 30 by means of conduits 32 and 34.

Conduit 6 is connected with a flowmeter cell 36. Spaced along cell 36are a pair of energy-sensitive devices 38 and 40. Radiant energy sources42 and 44, here shown schematically simply as incandescent lightfilament loops, are disposed to direct light through cell 36, preferablyat right angles to fluid flow, to fall upon the devices which aresensitive to the type of radiant energy used; in the embodiment shown,devices 38 and 40 are suitable conventional photoelectric cells. Theoutput signals from devices 38 and 40 go to a suitable electroniccounter 46 which may desirably be provided with an indicator or pointer48 adapted to cooperate with a scale 50 calibrated in any desired unitssuch as gallons per minute, cubic centimeters per second, or the like.

Liquid leaving cell 36 flows through a connected conduit 52 to a pointof use such as the pressure connection of a hydraulic motor, to areservoir, to a drain to waste, or the like.

OPERATION A gas bubble enters conduit 6 by way of the Y 8. The velocitygradient forces the bubble to the center of the flow stream where thevelocity is a maximum. As the bubble passes between energy source 42 andenergysensitive device 38, it interrupts the beam of radiant energy andcontinues through cell 36 to interrupt the beam between source 44 anddevice 40. The resulting signals from devices 38 and 40 go to counter 46which provides an instantaneous read-out. Counter 46 actually measuresthe time elapsed between interruptions of the radiant energy beamsfalling on devices 38 and 40, but may be calibrated as aforesaid interms of liquid flow.

Bubble size may be controlled by varying the pressure in source 18, thesize of tube 12, the capacitance of the system 30, 32, 34. The Y 8 ispreferably far enough upstream of cell 36 to assure that bubbleintroduction into the liquid stream will not unstabilize the liquidflow.

We wish it to be understood that we do not desire to ii. a source of airunder pressure connected with be limited to the exact details ofconstruction shown the supply port of the fluidic amplifier; anddescribed, for obvious modifications will occur to a iii, a ource ofcontrol pressure connected with Person Skilled in said control port ofthe fluidic amplifier;

whatlis Qlalmed is: 5 iv. a fluid conduit connecting an output port ofthe A q f flOWmeteTFOmPTISmEI fluidic amplifier with the remaining inputleg of a. a first llquidconduit adapted to be connected with Said and aP P q l under PTeSSPTe; f. means for measuring the time it takes for agas bubb. a llquld-conductmg (Y) having two input legs and ble to passthrough the elongated celL an output leg, one of said input legsconnected with said first conduit to receive liquid therefrom;

c. an elongated cell having a liquid flowpath therethrough and havinginput and output connections with said flowpath;

d. a second liquid conduit connecting the output leg of the (Y) with theinput connection of the elongated cell;

e. a source of air bubbles comprising:

i. a fluidic amplifier having supply, and output ports, and at least onecontrol port;

2. A flowmeter as in claim 1, in which a portion of the fluid conduitconnecting the fluidic amplifier with the (Y) is a capillary tube.

3. A flowmeter as in claim 2, in which the control pressure source is afluidic oscillator.

4. A flowmeter as in claim 1, in which the control pressure source is afluidic oscillator.

5. A flowmeter as in claim 1, wherein a capacitor is connected with thefluidic amplifier.

1. A liquid flowmeter comprising: a. a first liquid conduit adapted tobe connected with a source of liquid under pressure; b. aliquid-conducting (Y) having two input legs and an output leg, one ofsaid input legs connected with said first conduit to receive liquidtherefrom; c. an elongated cell having a liquid flowpath therethroughand having input and output connections with said flowpath; d. a secondliquid conduit connecting the output leg of the (Y) with the inputconnection of the elongated cell; e. a source of air bubbles comprising:i. a fluidic amplifier having supply, and output ports, and at least onecontrol port; ii. a source of air under pressure connected with thesupply port of the fluidic amplifier; iii. a source of control pressureconnected with said control port of the fluidic amplifier; iv. a fluidconduit connecting an output port of the fluidic amplifier with theremaining input leg of said (Y); and f. means for measuring the time ittakes for a gas bubble to pass through the elongated cell.
 2. Aflowmeter as in claim 1, in which a portion of the fluid conduitconnecting the fluidic amplifier with the (Y) is a capillary tube.
 3. Aflowmeter as in claim 2, in which the control pressure source is afluidic oscillator.
 4. A flowmeter as in claim 1, in which the controlpressure source is a fluidic oscillator.
 5. A flowmeter as in claim 1,wherein a capacitor is connected with the fluidic amplifier.